This invention relates to a virtual computer system that provides services to be executed by a plurality of virtual machines via a network and a technique to locate a part where performance has degraded in the virtual computer system and in particular, relates to improvement of a virtual computer system that provides cloud computing.
Economic globalization and consequent fiercer competition require continuous innovation in businesses. As to IT systems to support business activities, it is not uncommon that system constructions are requested within such an extremely short period as a month or two for new services to be released, so that companies take on heavy burden of costs to construct and maintain their own (in-house) IT systems. To cope with the problem, cloud computing, which is a service that a company outsources its IT system to a data center provider to use computer resources only for a required period, has come up as a service utilizing a wide area network (WAN) which is remarkable in recent years in broadening the bandwidth.
Service modes provided by the cloud computing are generally categorized into three cloud services depending on the flexibility of IT resources to be provided: IaaS (Infrastructure as a Service), PaaS (Platform as a Service), and SaaS (Software as a Service). IaaS is a cloud service for offering an infrastructure such as electric power, an installation site, and a network backbone. PaaS is a cloud service that a data center provider prepares hardware for IT equipment, virtual machine monitors (VMMs), virtual machines, and operating systems (OSs) in addition to the infrastructure to offer virtual machines to a company. SaaS is a service that a data center provider prepares business applications in addition to the virtual machines for the client company to rent them by hour.
Globally advanced cloud vendors offer services corresponding to PaaS or SaaS. Such vendors' services are commonly called public cloud and provided via the Internet. Public cloud allows a low-cost and quick preparation for start of services, but suffers from temporary congestion or disconnection in the Internet, so that it is difficult to provide stable services on an end-to-end (a terminal of a client to a business application) basis. On fears to the reliability, public cloud is not so popular for core business IT systems.
In contrast, WAN service utilizing a network service such as dedicated line provided by a carrier, IP-VPN, or wide area Ethernet instead of the Internet provides higher reliability and higher-quality communication compared with the Internet and suitable for core business IT systems. As a cloud service using the WAN, a service equivalent to PaaS is known that rents server resources in units of virtual machines (for example, Hitachi's Harmonious Cloud). PaaS using WAN advantageously establishes high reliability unlike the public cloud, so that PaaS can provide stable cloud services.
For a cloud service with the WAN and the PaaS combined (hereinafter, the specific cloud service), a data center provider provides communication infrastructures (WAN and LAN), server hardware, and virtual machines (or virtual servers) in a one stop. A client company is required to prepare only business applications to work in the virtual machines to use the service. In the specific cloud service, the client company accesses virtual machines in a data center from a client at its site via the WAN provided by a carrier tied-up with the data center provider.
In the specific cloud service, the WAN for providing the service, the LAN equipment in the data center, virtual machine monitors, and physical computers are shared by a plurality of companies. For this reason, if any problem occurs such as performance degradation in some business application used by some company, the part which has developed the performance degradation should be located promptly. The data center provider informs the section in charge of operation management of the part with the problem to eliminate or fix the performance degradation in the services. For example, if the source of the performance degradation in the services is the WAN, the provider needs to notify the tied-up carrier of the problem, or if the LAN equipment or the VMM in the data center is the source of the performance degradation, it needs to notify the PaaS operation management section in the data center, and if the business application running on the virtual machines itself is the source of the performance degradation, the data center provider needs to notify the client company which developed the business application.
To locate the source of performance degradation in a computer system, techniques in the following patent documents are known.
JP2002-374301A, in which a network is formed of a plurality of carriers, relates to monitoring the quality of communication at a relay node between carriers to notify the user of it. A fault in a WAN can be detected.
JP2006-65619A discloses a technique that sorts the source of a fault into a network and application servers. A fault in a LAN in a data center or a fault in a WAN can be detected.
US2009/024994A discloses a technique that obtains performance information on a physical server with a VMM configuring virtual computers and obtains performance information on virtual machines with an agent operated in the virtual machines to locate the part where performance has degraded in the virtual computers.
JP2001-195285A discloses a technique in a computer system including a server and LAN equipment that collects performance information on application programs running on the server and network traffic and performs multivariate analysis on the collected information to presume the part which has developed a fault based on a predetermined correlationship.